This invention relates in general to in-track registration control for receiver members in electrostatographic reproduction apparatus or the like, and more particularly to in-track registration control for receiver members employing a feedback loop for immediacy of registration error correction and improved in-track registration accuracy over the long term.
In modern high speed electrostatographic reproduction apparatus, such as copiers and printers or the like, a marking particle developed image corresponding to information to be reproduced is transferred to a receiver member to form a desired reproduction. The receiver member is, for example, a cut sheet of plain bond paper. The receiver member is fed from a supply stack into association with that portion of the electrostatographic reproduction apparatus bearing the marking particle developed image. It is essential that the feed and transport of the receiver member be controlled in such a manner so as to present the receiver member into association with the marking particle developed image within a specified window of time in order to form an acceptable reproduction on the receiver member.
In the operation of electrostatographic apparatus, it is common practice in feeding and transporting receiver members to remove a receiver member from the supply stack at a preselected time, and feed the receiver member, by means of driven nip rollers for example, along a transport path to a registration gate where the member is momentarily stopped. The receiver member is then released by the gate at a specified time so as to be transported therefrom into association with the marking particle developed image in in-track register for aligned transfer of the marking particle image to the receiver member. As shown for example in U.S. Pat. No. 3,575,411 (issued Apr. 20, 1971, in the name of Kastelic), variability in the timing of transport of the receiver member in the in-track direction to the registration gate relative to a given time for a receiver member travel from the supply to the registration gate can be and the transport apparatus effectively controlled to speed up or slow down the receiver member. However, such control looks only at the absolute travel time for the receiver member; it does not take into account tolerances in the feed and transport elements or wear of such elements over time. As a result, no overall adjustment to immediately correct for element errors and improve in-track registration control accuracy over the long term is possible.